The present invention relates to a composite component having a sandwich structure which is made up of at least one core positioned between two outer layers. A casting resin system penetrates into the outer layers at least partially, and the layers are bonded together by press molding. The present invention also relates to a process for the production of such a composite component.
Lightweight composite components having a sandwich structure, made up of a core having a honeycomb or corrugated structure, made for example from paper, aluminum or plastic, and a lower and upper outer layer composed of fiber mats, made for example from natural, glass, plastic or carbon fibers, are known from EP 1 319 503 A, for example. Owing to their low weight per unit area and their high flexural strength with low wall thickness, they are used as interior trim in automotive construction, for example. The fiber mats constituting the lower and upper outer layer are wetted with a two-component polyurethane (PU) system, for example, which penetrates into part or all of the core. The PU system, which can be readily foaming, for example, shapes and bonds the outer layers to the core.
These sandwich composite components are manufactured by the compression molding process. The entire surface of both sides of the sandwich structure comprising core and outer layers is sprayed with the two-component PU system, and the structure is placed in the mold, which is generally heated to 60 to 160° C., preferably 120 to 140° C., and press molded. After being released from the mold and cooled, the composite components can be punched, milled or laminated, for example, if required.
The integration of screw connections, partial metal reinforcements, joining elements, fixing or similar elements, is only possible within limits. For example, during production of the composite component in the compression mold, the inserts can be positioned appropriately and bonded to the composite component by the foaming and curing PU system during press molding. The inserts can also be completely enclosed in the composite component by placing an outer layer, e.g. a fiber mat, on top of the insert and pressing it onto the insert during press molding.
The joining of molded parts, made from plastic, for example, to the lightweight composite component by welding is also known. This is relatively complex, however, since the molded parts first have to be produced separately and then introduced into a welding tool for welding. In addition, the quality of the welded joint is very much dependent on the materials that are used.
The encapsulation of such sandwich composite components with free-flowing materials such as polyurethane is also known. The disadvantage of these composite components injection molded with PU is their relatively low rigidity and strength. Furthermore, the selective injection molding of individual areas of the composite component with the crosslinking PU resin system is difficult. The formation of flashes in the injection molded PU also requires costly secondary finishing. Finally, an injection molded PU surface does not satisfy the optical requirements for certain applications and cannot be pigmented.